Precision is the key requirement for adjusting shims.Accurate
adjustment for fuel quantity si completed depending on grouping of
products.We adopt high precision optical ruler to control lapping
dimension, and can control product precision dimension within
0.002mm.We finish grouping by inspecting one product with two
products inside dustfree workshop.One product is measured for no
less than 5 times from finishing process to finished product
(Testing methods:use high precision digital display micrometer to
measure conformity between actual dimension and required
dimension,and whether the dimension for same grouped products is
same or not.)

2. Geometric tolerance

Geometric tolerance of adjusting shims is directly related to the
maintenance quality of fuel injectors.Main geometri tolerance
requirement for adjusting shims is depth of parallelism.Large shim
will affect product tightness while small shim will affect
reliability and stability of products.We adopt high-precision
double-sided lapping machine to ensure and control depth of
parallelism for products within 0.002mm.Adoption of one-time
forming process better ensures product axiality(Testing methods:use
parallelism tester and deflection instrument to test parallelism
depth and axiality respectively)